Transmission power correcting method, mobile communications system and mobile station

ABSTRACT

A mobile station in a mobile communications system directs a base station to raise a transmission power using identification data, when a reception quality measured by the mobile station is lower than a desired reception quality. The mobile station also directs the base station to lower the transmission power using identification data, when the reception quality measured by the mobile station is higher than the desired reception quality.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to transmission power correctingmethods, mobile communications system, and mobile stations, and, moreparticularly, to a transmission power correcting method, a mobilecommunications system and a mobile station in which a transmission powerof a source of transmission is corrected, based on a reception qualitymeasured at a destination of transmission.

2. Description of the Related Art

For downstream transmission in a mobile communications system, i.e. datatransmission from a base station to a mobile station, a technology knownas high speed downlink packet access (HSDPA) is used for high-speed,large-volume downloading. A discussion on HSPDA underway in 3rdGeneration Partnership Project (3GPP) is directed to changing of amodulation scheme and a Turbo coding rate in accordance with the qualityof reception at a mobile station. In changing a modulation scheme and aTurbo coding rate, it is necessary for a base station to notify a mobilestation of the modulation scheme and the Turbo coding rate to be used.Particularly, in adaptive modulation coding (AMC) in which a modulationscheme and a Turbo coding rate are adaptively changed, transmission(signaling) of information related to the modulation coding scheme fromthe base station to the mobile station occurs frequently.

3GPP Technical Report (TR) 25.858V1.0.0 “8 Associated Signaling”(hereinafter, referred to as reference 1) gives a description of asignaling procedure related to this signaling. Information related tothe modulation coding scheme includes transport-format and resourcecombination (TFRC).

FIG. 10 shows an example of TFRC list given in reference 1. The list isprovided in a portion of reference 1 where uplink signaling isdescribed. The list lists substantially the same information related tothe modulation coding scheme transmitted from the base station to themobile station in downlink signaling. The list lists combinations of amodulation scheme, a transport block set (TBS) size and the number ofcodes. The modulation scheme may be one of two digital modulationschemes including quaternary phase shift keying and (QPSK) and 16quadrature amplitude modulation (QAM). A TBS size indicates the datasize of a transport block (TrBlk) included in a frame multiplied by thenumber of blocks. That is, the TBS size indicates the data size of aframe. A TBS size is a parameter related to Turbo coding and is one typeof information related to modulation coding scheme. It is assumed herethat a multicode scheme, in which a plurality of channelization codes(spreading codes) are assigned to a mobile station, is used. The listlists the number of codes included in a multicode (in the illustrationthe number of codes is 5).

For example, TFRC1 includes parameters such that modulation scheme=QPSK,TBS size=1200 bit and number of codes=5. In the case of TFRC6,modulation scheme=16 QAM, TBS size=7200 bit and number of codes=5.Assuming that spreading factor (SF)=16 and one frame=2 ms, the volume ofdata per frame is 4800 bits when modulation scheme=QPSK, 9600 bits whenmodulation scheme=16 QAM. The Turbo coding rate is ¼ for TFRC(1), ½ forTFRC(2), ¾ for TFRC(3), ½ for TFRC(4), ⅝ for TFRC(5) and ¾ for TFRC(6).The information given above is not immediately available from the tableof FIG. 10, though.

In transmitting the information (TFRC, according to reference 1) relatedto the modulation coding scheme from the base station to the mobilestation, instead of transmitting the information as it is,identification data having a smaller data volume is transmitted.Identification data corresponds to transport-format and resource relatedinformation (TFRI) of reference 1. The data volume of TFRI is defined inreference 1 as follows.

-   Channelization code set: 7 bits-   Modulation scheme: 1 bit-   Transport block set size: 6 bits

A channelization code set indicates a combination of a plurality ofchannelization codes assigned to a mobile station according to amulticode scheme. FIG. 10, listing TFRCs, would not be complete withoutlisting channelization code sets instead of only the number of codes.FIG. 10, however, serves the purpose since it corresponds to a specialcase where the number of codes is fixed to 5. Therefore, only the numberof codes is given.

Traffic between the base station and the mobile station is reduced byemploying an information transmission scheme in which the informationrelated to the modulation coding scheme is converted into theidentification data.

The mobile station of the mobile communications system measures thequality of reception. By feeding back the result of measurement to thebase station, the transmission power of the base station is corrected toan appropriate level. More specifically, uplink signaling from themobile station is used to inform the base station of a power offsetvalue, based on the quality of reception measured by the mobile station.In accordance with the information obtained through signaling, the basestation corrects the transmission power.

FIG. 11 shows a table of reference 1 listing power offset values. Thetable of FIG. 11 lists a plurality of power offset values for each TFRClisted in FIG. 10. An identification code is associated with each set ofa TFRC and the power offset value. Power offset=0 dB is used as adefault value in each set of a TFRC and a power offset value. Referringto FIG. 11, power offset values of 1 dB and 2 dB are prescribed forTFRC(2)-TFRC(6) other than the default power offset value of 0 dB. ForTFRC(1), in addition to 0 dB, the power offset values up to 12 dB insteps of 1 dB are provided. By transmitting a desired power offset shownin FIG. 11 to the base station, based on the quality of receptionmeasured by the mobile station, the power of transmission from the basestation is subject to fine control so that the throughput of the entiresystem is improved.

However, in a system configuration as described in reference 1, wherethe mobile station only notifies the base station of an increase in thetransmission power, the transmission power requested may exceed thetotal power, i.e. power rating, of the base station. Anotherdisadvantage with the related-art system configuration is that,performing only an increase in the transmission power of the basestation may induce an adverse effect of intra-cell interference orinter-cell interference.

SUMMARY OF THE INVENTION

Accordingly, a general object of the present invention is to provide atransmission power correcting method, a mobile communications system anda mobile station in which the aforementioned disadvantages of therelated art are eliminated.

Another and more specific object is to provide a transmission powercorrecting method, a mobile communications system and a mobile stationin which it is possible to improve the throughput of the entire systemwhile controlling intra-cell interference or inter-cell interference.

The aforementioned objects can be achieved by a transmission powercorrecting method or a mobile communication system, in which the sourceof transmission is directed to raise the transmission power when thereception quality measured at the destination of transmission is lowerthan a desired reception quality and to lower the transmission powerwhen the reception quality measured at the destination of transmissionis higher than the desired reception quality.

According to the transmission power correcting method or the mobilecommunications system of the present invention, the transmission powermay be reduced instead of raised as such a requirement arises. Since thetransmission power is variable according to a requirement, power controlcapable of preventing the transmission power from exceeding a powerrating of a base station is possible so that the total throughput isimproved. Since the total power in a base station is reduced, intra-cellinterference and inter-cell interference are controlled. The sameadvantages of improved throughput and controlling of intra-cellinterference and inter-cell interference are also available from amobile station according to the invention.

By allowing the mobile station to direct the base station to lower atransmission power, when a modulation scheme providing the lowestreception quality is being used and when a reception quality measured ishigher than a desired reception quality, the transmission power isreduced only when the modulation scheme with the lowest receptionquality fails to deal with such a situation. Accordingly, theconstruction of a system is simplified.

By reducing the number of spreading codes used instead of raising thetransmission power for each code, an increase in the total power iscontrolled.

By configuring the base station, receiving a request to reduce thenumber of spreading codes and an instruction to raise the transmissionpower, to correct the number of spreading codes and the transmissionpower so that the total power does not exceed a power rating, a morepractical system is provided.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and further features of the present invention will beapparent from the following detailed description when read inconjunction with the accompanying drawings, in which:

FIG. 1 shows a mobile communications system according to a firstembodiment of the present invention;

FIG. 2 is a block diagram showing a configuration of a mobile station ofFIG. 1;

FIG. 3 is a block diagram showing a configuration of a base station ofFIG. 1;

FIG. 4 shows a table listing power offset values provided by the mobilestation to the base station;

FIG. 5(a) shows a BLER-{circumflex over ( )}Ior/Ioc characteristic;

FIG. 5(b) shows a BLER-{circumflex over ( )}Ior/Ioc characteristic witha power offset value used as a parameter;

FIG. 6 shows default transmission power distribution in a base station;

FIG. 7 shows transmission power distribution introduced in a basestation when available power is reduced;

FIG. 8 shows transmission power distribution in a base station accordingto a second embodiment of the present invention;

FIG. 9 is a table listing correspondence between power offset values andantilogarithms;

FIG. 10 is a list of TFRCs given in reference 1; and

FIG. 11 is a table listing power offset values given in reference 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a construction of a mobile communications system accordingto a first embodiment. The communications system comprises a mobilestation 11, a base station 12 and a base station controller 13. Themobile station 11 is capable of communicating with the base station 12as it is being moved by the user carrying the mobile station 11. Thebase station 12 is equipment installed at a predefined location and iscapable of simultaneous wireless communication with a plurality ofmobile stations 11. The base station 12 is connected to a base stationcontroller 13 hosting the base station 12 via a cable for transmissionbetween the base station 12 and the base station controller 13. The basestation 12 is responsible for connecting the mobile station 11 to a wirecommunication circuit. The base station controller 13 is connected to aplurality of base stations 12 and responsible for various types ofcontrol related to the base station 12. The base station controller 13is also responsible for connecting the mobile station 11 to the publiccircuit network via the base station 12.

In the mobile communications system shown in FIG. 1, a signaloriginating from the mobile station 11 is transmitted to a destinationof communication via the base station 12, the base station controller 13and the public circuit network (not shown). A signal originating fromthe destination of communication is transmitted to the mobile station 11via the public circuit network, the base station controller 13 and thebase station 12.

FIG. 2 shows a construction of the mobile station of FIG. 1. The mobilestation comprises an antenna 21, a transceiver 22, a despreading unit23, a demapping unit 24, a deinterleaving unit 25, a channel decodingunit 26, a channel quality measuring unit 31, a converting unit 32, achannel coding unit 33, an interleaving unit 34 and a spread spectrummodulating unit 35. The channel decoding unit 26 is provided with a ratede-matching unit 27 and a Turbo decoding unit 28.

A description will now be given of the operation of reception in themobile station.

A radio signal arriving from the base station is received by the antenna21, the frequency thereof being converted by the transceiver 22 from aradio frequency to a base band frequency, which is then input to thedespreading unit 23. The despreading unit 23 subjects the signal outputfrom the transceiver 22 to a despreading process using a channelizationcode requested by the base station. The despread signal is output to thedemapping unit 24. The demapping unit 24 subjects the signal output fromthe despreading unit 23 to conversion from an IQ symbol to bits, using amodulation scheme (QPSK/16 QAM) requested by the base station. When QPSKis used, two bits are output. When 16 QAM is used, four bits are output.The signal output from the demapping unit 24 is subject to adeinterleaving process by the deinterleaving unit 25. The signal fromthe deinterleaving unit 25 is output to the channel decoding unit 26.The rate dematching unit 27 of the channel decoding unit 26 subjects thesignal output from the deinterleaving unit 25 to a rate dematchingprocess. The signal from the rate dematching unit 27 is subject to aTurbo decoding process by the Turbo decoding unit 28. The signal outputfrom the rate dematching unit 26 is output to another processing blockin the mobile station.

A description will now be given of the operation of transmission in themobile station.

The channel quality measuring unit 31 is supplied with the signal fromthe reception system described above so as to measure the quality ofreception of the signal arriving from the base station channel bychannel. The channel quality measuring unit 31 determines a power offsetto be provided to the base station, based on the result of measurement.The conversion unit 32 converts TFRC, ACK/NACK, PILOT, TFCI and TPC thatinclude a power offset value output from the channel quality measuringunit 31 into respective identification data so as to output theidentification data to the spread spectrum modulating unit 35 via adedicated physical control channel (DPCCH). Information data is subjectto the Turbo coding process and the rate matching process in the channelcoding unit 33. The data output from the channel coding unit 33 issubject to the interleaving process by the interleaving unit 34. Thesignal from the interleaving unit 34 is output to the spread spectrummodulating unit 35 via a dedicated physical data channel (DPDCH). TheDPCCH data and the DPDCH data are subject to a predetermined spreadingprocess by the spread spectrum modulating unit 35 for digital modulationaccording to a predetermined modulation scheme. The signal output fromthe spread spectrum modulating unit 35 is subject by the transceiver 22to frequency conversion whereby a baseband frequency is converted into aradio frequency. The signal at the radio frequency is transmitted fromthe antenna 21.

ACK/NACK indicates an acknowledge/negative acknowledge signal indicatingto the base station whether downlink reception data is properlytransmitted. PILOT indicates a PILOT signal providing a reference fortiming/phase to be learned by the base station. TFCI indicates atransport format combination indicator signal indicating a combinationof transport formats. TPC indicates a transmit power control signalprovided for downlink transmission power control.

FIG. 3 shows a construction of the base station shown in FIG. 1. Thebase station comprises a downlink packet channel (HS-DSCH) transmissionprocess unit 41, a common pilot channel (CPICH) transmission processunit 42, a transmission process unit 43 for another channel, amultiplexing unit 44, a transceiver 45, an antenna 46, a despreadingunit 63, a deinterleaving unit 64, a channel decoding unit 65, aconverting unit 66, a scheduler 67 and a resource management unit 68.The downlink packet channel transmission process unit 41 is providedwith a channel coding unit 51, an interleaving unit 52, a modulatingunit 53, a multiplier unit 54 and a multiplexing unit 55. The channelcoding unit 51 is provided with a Turbo coding unit 56 and a ratematching unit 57.

A description will now be given of the operation of reception in thebase station.

The radio signal arriving from the mobile station is received by theantenna 46 and subject by the transceiver 45 to frequency conversionwhereby a radio frequency is converted into a baseband signal. Thesignal output from the transceiver 45 is subject by the despreading unit63 to a despreading process using a predetermined spreading code. TheDPDCH data included in the data subjected to the despreading process isoutput to the deinterleaving unit 64 and the DPCCH data is output to theconverting unit 66. The DPDCH data is subject to a deinterleavingprocess by the deinterleaving unit 64 and to a rate matching process anda Turbo decoding process by the channel decoding unit 65. The datasubjected to the Turbo decoding process is transmitted to the basestation controller hosting the base station. The DPCCH data includesidentification data produced in a conversion step in the mobile station.The DPCCH data is converted into original TFRC, ACK/NACK, PILOT, TFCI,TPC. The TFRC, which include a power offset value, is output by thescheduler 67 to the resource management unit 68 under predeterminedtiming control. The resource management unit 68 manages the TFRCs foreach of the plurality of mobile stations. In the resource managementunit 68, the TFRC stored in the resource management unit 68 is replacedby the TFRC output from the scheduler 67. The resource management unit68 informs the channel coding unit 51 of a coding rate, informs themodulating unit 53 of a channelization code set and a coding scheme, andinforms the multiplier 54 of a power offset value.

A description will now be given of the operation of transmission fromthe base station.

The signal transmitted from the base station controller hosting the basestation is subject to a Turbo coding process in the Turbo coding unit 56and to a rate matching process in the rate matching unit 57. The channelcoding unit 51 comprising the Turbo coding unit 56 and the rate matchingunit 57 controls a combined coding rate of Turbo coding and ratematching to match the coding rate requested by the resource managementunit 68. The signal output from the channel coding unit 51 is subject toan interleaving process by the interleaving unit 52. The signalsubjected to the interleaving process is output to the modulating unit53. The modulating unit 53 performs a digital modulation process(conversion from bits into IQ symbols), using a modulation schemerequested by the resource management unit 68. The modulating unit 53performs a spreading process using the channelization code requested bythe resource management unit 68. The signal for each channel output fromthe modulating unit 53 is multiplied in the multiplier 54 by a gaincorresponding to the power offset value. The signal output from themultiplier 54 is multiplexed by the multiplexer 55. The signal outputfrom the multiplexer 55 is multiplexed with the CPICH data and thesignals of the other channels by the multiplexer 44. The signal outputfrom the multiplexer 44 is subject by the transceiver 45 to frequencyconversion whereby a baseband frequency is converted into a radiofrequency for radio transmission from the antenna 46 to the mobilestation.

FIG. 4 shows a table listing power offset values reported from themobile station to the base station. In addition to the power offsetvalues, the table of FIG. 4 lists TFRC(x,y) corresponding to informationother than the power offset and indicating a TFRC type. The table listsidentification data in association with each combination of TFRC(x,y)and power offset value. x of TFRC(x,y) in FIG. 4 is the same as x ofTRC(x) in FIG. 10, where x=1−6. y indicates the number of codes in amulticode, where y=1−15. For each set of TFRCs with the same number x,where y may take any value, the power offset=0 dB is used as a default.For TFRC(2,y)-TFRC(5,y), power offset values of 1 dB and 2 dB are usedin addition to the default power offset value of 0 dB. For TFRC(1), inaddition to 0 dB, the power offset values up to 12 dB in steps of 1 dBare used.

For TFRC(6,y), a set of power offset values −1 dB, −2 dB, −3 dB and −4dB are provided in addition to the power offset values of 0 dB, 1 dB and2 dB. By providing TFRC(6,y) with negative power offset values, it ispossible to reduce the power of transmission from the base station whenthe mobile station is located in the neighborhood of the base station.Accordingly, the level of interference with other channels belonging tothe same cell or interference with other cells is reduced.

FIG. 5(a) shows a BLER characteristic with respect to Ior/Ioc, and FIG.5(b) shows a BLER characteristic with respect to Ior/Ioc using poweroffset values as parameters. A description of FIG. 5(a) will be given.{circumflex over ( )}Ior and Ioc of {circumflex over ( )}Ior/Ioc aredefined in 3GPP TS25.101V3.8.0 as follows.

{circumflex over ( )}Ior: Spectral density of downlink received powermeasured by a mobile station antenna connector. Ioc: Spectral density ofbandwidth-limited white noise power measured by a mobile station antennaconnector.

BLER indicates a block error rate. The characteristic provided bydifferent TFRCs is described in 3GPP TR25.848V4.0.0. In the descendingorder of levels of BLER characteristic, TFRCs are arranged such thatTFRC(1,y), TFRC(2,y), TFRC(3,y), TFRC(4,y), TFRC(5,y), TFRC(6,y), wherey may take any value. A TFRC with a good BLER characteristic means aTFRC requiring a low level of {circumflex over ( )}Ior/Ioc for a givenBLER. The channel quality measuring unit 31 of the mobile station 11measures the characteristic described above. TFRC used in downlinktransmission from the base station to the mobile station is determinedby level comparison between the measured characteristic and thresholdvalues th1, th2, th3, th4 and th5. The threshold values are arrangedsuch that th1, th2, th3, th4 and th5 in the ascending order of levels.TFRC(1,y) provides the best BLER characteristic since it requires aminimum lelvel of {circumflex over ( )}Ior/Ioc. Accordingly, TFRC(1,y)is assigned to a mobile station located at a cell edge (cell boundary).TFRC(2,y)-TFRC(5,y) are assigned to the other mobile stations locatedsuccessively closer to the base station. The most inward mobile station,i.e. the mobile station closest to the base station is assignedTRC(6,y).

A description will now be given of FIG. 5(b). The power offset valuesare arranged such that 0 dB, 1 dB, 2 dB, . . . , 12 dB in the descendingorder of excellence of BLER characteristic. The power offset value to beprovided from the base station to the mobile station is determined bylevel comparison with threshold values th11, th21, th31, . . . , th131.

FIG. 6 shows default transmission power distribution in a base station.It is assumed here that the number of codes=10 in a downlink packetchannel (HS-DSCH). Of the power rating Pt(100%) of the base station, amaximum of 80% is assigned to the HS-DSCH, a maximum of 10% is assignedto the common pilot channel (CPICH), and 10% is permanently assigned tothe other channels. The other channels include an individual physicalchannel for individual users, and a common control channel. The totalHS-DSCH power P_(hs) is assigned to two users (two mobile stations). Acode set 71 including 5 codes is assigned to user 1 and a code set 72including 5 codes are assigned to user 2. A distributed power ofP_(hs)/10 resulting from division-by-10 of the total HS-DSCH power Phsis assigned to a code of HS-DSCH.

FIG. 7 shows transmission power distribution introduced when theavailable power is decreased. As in FIG. 6, of the total power Pt(100%)of the base station, a maximum of 80% is assigned to the HS-DSCH, 10% ispermanently assigned to the common pilot channel (CPICH), and a maximumof 10% is assigned to the other channels. The total HS-DSCH power P_(hs)is assigned to two users, five codes are assigned to user 1 and fivecodes are assigned to user 2. Referring to FIG. 4, assuming that user 1is assigned TFRC(1,y) and power offset value=0 dB, and user 2 isassigned TFRC(6,y) and power offset value=−4 dB, the power assigned tocode set 71 for user 1 remains Phs/2. The power assigned to the code set72 for user 2 is dropped by 4 dB from P_(hs)/2 to P_(hs)*10−0.4/2.Accordingly, the HS-DSCH power is reduced.

Since the portion occupied by the HS-DSCH power in the base stationpower is relatively large, the above arrangement makes it possible toreduce intra-cell interference and inter-cell interference. Orthogonalcodes are used in each of the channels in a given cell. Accordingly,intra-cell interference is theoretically 0 under a single-pathenvironment. In an actual cellular environment, intra-cell interferencecaused by geographical reflection and diffraction presents a seriousproblem. By reducing the HS-DSCH power according to the embodimentdescribed above, adverse effects from interference with other users andother channels are successfully controlled.

Second Embodiment

FIG. 8 shows distribution of base station power according to a secondembodiment of the present invention. Of the total power Pt(100%) of thebase station, a maximum of 80% is assigned to the total HS-DSCH power,10% is permanently assigned to the common pilot channel(CPICH) and amaximum of 10% is assigned to the other channels. The default powerdistribution is the same as that shown in FIG. 6. According to thesecond embodiment, the power distribution as shown in FIG. 8 introduced.Referring to FIG. 8, the total HS-DSCH power P_(hs) is assigned to twousers. The code set 71 comprising five codes is assigned to user 1 andthe code set 72 comprising one code is assigned to user 2. Referring toFIG. 4, assuming that user 1 is assigned TFRC(1,y) and power offsetvalue=0 dB and user 2 is assigned TFRC(1,y) and power offset value=7 dB,the power assigned to the code set 71 for user 1 is P_(hs)/2 and thepower assigned to the code set 72 for user 2 is P_(hs)/2. While thepower per code for user 1 is P_(hs)/10, the same level as shown in FIG.6, the power per code for user 2 is Phs/2, an substantial increase fromthe power level of FIG. 6.

Varying the number of codes is especially useful when the receptionquality measured by the mobile station is lower than a desired receptionquality. By allowing the mobile station to direct the base station toreduce the number of spreading codes used and to raise the transmissionpower, it is ensured that the quality of reception in the mobile stationis improved. That is, under a given condition of total power, he numberof codes in a multicode is changed so that the per-code powerdistribution is changed. The other aspects of the configuration andoperation are the same as those of the first embodiment so that thedescription thereof is omitted.

FIG. 9 shows a table listing power offset values in association withantilogarithms. As described above, in order to distribute the power ina given condition of total power, a requirement is that a sum ofantilogarithms of power offset values for each channel does not exceedthe number of codes provided in the base station (for example, 10 or15). As long as this requirement is met, the power can be distributed asdesired. An example for a case of 10 codes is shown in FIG. 8. In a caseof 15 codes, user 1 may be assigned the number of codes of 1 and a 10 dBoffset, and user 2 may be assigned the number of codes of 5 and a 0 dBoffset.

As described above, the mobile station is allowed to direct the basestation to reduce the number of spreading codes used in addition todirecting the base station to raise the transmission power, when thereception quality measured by the mobile station is lower than a desiredreception quality. Conversely, the mobile station may be allowed todirect the base station to increase the number of spreading codes usedand to lower the transmission power, when the reception quality measuredin the mobile station is higher than the desired reception quality. Thetotal HS-DSCH power may be assigned a portion other than “a maximum of80%”. The invention is also useful in a configuration in which the powerratio with respect to CPICH is not constant.

The present invention is not limited to the above-described embodiments,and variations and modifications may be made without departing from thescope of the present invention.

1-7. (canceled)
 8. A method of transmission power control, comprisingthe step of: identifying, by a mobile station, a transport block setsize and a modulation scheme to a base station, said transport block setsize and said modulation scheme being based on a quality of a signaltransmitted from base station and received by the mobile station;identifying, by a mobile station, a transmission power correction valueto the base station, wherein said transmission power correction valuecorresponds to the transport block set size and the modulation scheme,and said transmission power correction value is a negative value whenthe transport block set size is a predetermined maximum size, and whenthe modulation scheme is 16 QAM; and correcting a transmission powerfrom the base station to the mobile station based on the identifiedtransmission power correction value.
 9. The transmission power controlmethod according to claim 8, wherein said step of identifying atransmission power correction value comprises: identifying the negativevalue only when the transport block set size to be determined is thepredetermined maximum size.
 10. The transmission power control methodaccording to claim 8, wherein said step of identifying a transmissionpower correction value comprises: identifying the transmission powercorrection value as identification data.
 11. The transmission powercontrol method according to claim 9, wherein said step of identifying atransmission power correction value comprises: identifying thetransmission power correction value as identification data.
 12. A mobilestation, comprising: an identification device configured to identify atransport block set size and a modulation scheme to a base station, saidtransport block set size and said modulation scheme being based on aquality of a signal transmitted from base station and received by themobile station; and an identification device configured to identify atransmission power correction value to the base station, wherein saidtransmission power correction value corresponds to the transport blockset size and the modulation scheme, and said transmission powercorrection value is a negative value when the transport block set sizeis a predetermined maximum size, and when the modulation scheme is 16QAM.
 13. A base station, comprising: a correction device configured tocorrect a transmission power from the base station to a mobile stationbased on a transmission power correction value identified by mobile,wherein said transmission power correction value corresponds to thetransport block set size and the modulation scheme, said transmissionpower correction value is a negative value when the transport block setsize is a predetermined maximum size, and when the modulation scheme is16 QAM, and said transport block set size and said modulation scheme isbased on a quality of a signal transmitted from the base station andreceived by the mobile station.